Filter device

ABSTRACT

The invention relates to a filter device, in particular for filter¬ing lubrication, consisting of at least one filter insert ( 19 ), in which a respec¬tive filter material ( 27 ) is received and which is provided with fluid passage points ( 70 ) that are delimited by wall parts ( 63 ) of the filter insert ( 19 ) and with a backflush device ( 37, 49 ) that has at least one flush nozzle ( 49 ), said flush nozzle being movable along the interior of the respective pairable filter insert ( 19 ) by means of a hollow drive shaft ( 37 ). The invention is character¬ized in that at least one pair of flush nozzles ( 49 ) is provided for each filter insert ( 19, 21 ), said flush nozzles having longitudinal slots ( 73, 74 ) which are arranged one over the other in the axial direction of the drive shaft ( 37 ), wherein the longitudinal slots have an offset relative to one another which runs transversely to the axial direction such that for adjacent flush nozzles ( 49 ), at least one part of the longitudinal slot ( 73 ) of one flush nozzle ( 49 ) overlaps with at least one of the fluid passage points ( 70 ) of the pairable filter insert ( 19, 21 ) and at least one part of the longitudinal slot ( 74 ) of the other flush nozzle ( 49 ) at least partly overlaps with the wall parts ( 63 ) which delimit the aforementioned fluid passage point of the filter insert ( 19, 21 ).

The invention concerns a filter device, in particular for the filtration of lubricating oil, comprised of at least one filter insert that retains a filter material, wherein said filter insert is provided with fluid passages, which are constricted by wall parts of said filter insert, and a backflush device with at least one flushing nozzle, which is displaceable along the inside of the respective associated filter insert by means of a hollow drive shaft.

Keeping the lubricating oil in perfect condition is of major significance for the operational reliability and life span of combustion engines. In particular the continuous operation of diesel engines which, for example in maritime applications, are operated with heavy fuel oil, make particularly high demands on the condition of the lubricating oil, which makes the use of filter devices for cleaning the lubricating oil in applications of this kind essential. The prior art in this respect is to use filter devices where the filter inserts can be backflushed to achieve longer operating times between filter insert changes and thus keep maintenance costs low. An example of such a filter device is described in DE 202016 003 089 U1.

It is the object of the invention to provide a filter device of this kind, which is characterized by particularly advantageous operating characteristics, especially when in backflush mode.

This object is met by a filter device that exhibits the characteristics of claim 1 in its entirety.

According to the characterizing part of claim 1, a significant feature of the invention is that at least one pair of flushing nozzles is provided for each filter insert, wherein said flushing nozzles are provided with longitudinal slots that are arranged in axial direction of the drive shaft one above the other, which are offset towards each other transverse to the axial direction in such a way that, for adjacently disposed flushing nozzles, at least part of the longitudinal slot of the one flushing nozzle overlaps with at least one of the fluid passages of the assignable filter insert, and at least part of the longitudinal slot of the other flushing nozzle overlaps at least partially the wall parts of this filter insert that constrict the fluid passage.

Of the flow paths, which are available for the backflush flow and which are constricted at the fluid passages by the wall parts of the filter insert, one flow path is open whilst the flow path at the following fluid passage is closed in this arrangement. Thus, with a continuous rotation of the flushing nozzle pairs, the backflush flows merge into each other through the overlap of the backflushing nozzles so that it settles into a continuous backflush volume. As a result of the backflush action that is pulsation-dampened in this manner, the pulsating force applied to the respective flushing nozzle, caused by the repeated flow interruption, is avoided. Since a pair of offset flushing nozzles is provided for each filter insert, the advantageous pulsation-damping action can also be achieved in filter devices with only a single filter insert.

In advantageous exemplary embodiments the respective filter insert is provided with a filter housing with two housing walls that are disposed concentrically to the longitudinal axis of the filter insert, wherein the filter material extends between said housing walls, which are penetrated by window-like fluid passages.

The arrangement is advantageously provided such that each pair of flushing nozzles passes over the adjacently disposed fluid passages in the filter housing by means of the motor-driven drive shaft of the backflush device in succession along the inside of the respective associable, cylindrical filter insert in a rotatory manner.

In particularly advantageous exemplary embodiments the drive shaft is provided with a guide device for each pair of flushing nozzles that protrudes in the direction towards the associable filter housing, wherein the respective flushing nozzle engages with said guide device and is guided in a longitudinally displaceable manner, and wherein said flushing nozzle is pressed against the inside of said filter housing by way of an energy store. This allows for a particularly secure and soft seating of the respective nozzle pair on the drive shaft, and jamming or tilting is avoided due to the guide device.

The energy store may advantageously be provided in form of an elastic sealing ring, which presses with its one side against the drive shaft and with its other side against the respective flushing nozzle.

In particularly advantageous exemplary embodiments a pair of flushing nozzles is combined into a single unit which, with its internal cross-section in radial direction, ends in the hollow drive shaft via the guide device, and with its outer cross-section in radial direction leads into a longitudinal slot which, with respect to its dimensions, is adapted to the geometry of the respective fluid passage that is passed over.

The arrangement may advantageously be such that both housing walls of a filter housing, which act as supports, are closed at their opposing ends by an annular end part, which comprises a fluid compartment for holding unfiltrate, wherein an annular separating wall passes through the filter housing between the two supports, wherein said separating wall is preferably formed by an internal and an external support ring. The components that form the filter housing may advantageously be made from injection-molded plastic, such as PA6.

Longitudinal rods may extend for each housing wall between the end parts and the separating wall located in between, wherein said longitudinal rods enclose the window-like fluid passages cage-like in the filter housing between them.

The two longitudinal slots of a pair of flushing nozzles may be offset with respect to each other so that, in conjunction with the cage arrangement of the fluid passages, there is always a flow path open, at least partially, preferably fully, via the one flushing nozzle, whilst the flow path into the other flushing nozzle is at least partially, preferably fully, closed so that during a continuous rotation of the drive shaft of the backflush device there is always a continuous flow through one of the two flushing nozzles of a pair from the filtrate side.

In a particularly advantageous manner, the internal longitudinal rods of the cage arrangement, located adjacent to the respective pair of flushing nozzles, may be slanted with respect to the radial direction so that they force a flow direction for each fluid passage of a filter insert, which is slanted by a predeterminable angle with respect to the inflow direction of the respective longitudinal slot of a pair of flushing nozzles. This causes an oblique flow through the filter medium, which facilitates the dislodging of contaminants.

The arrangement is advantageously designed such that the filtration takes place from the inside of the respective filter insert to the outside, that the backflushing action of the respective filter insert takes place from outside to inside, and that the resulting backflush volumes can be discharged from the filter device via the backflush device, wherein the respective filter insert is disposed stationary in a device housing, which comprises a fluid inlet for unfiltrate, a fluid outlet for filtrate and a discharge connection for the respective backflush volume.

Of particular advantage may be to use multiple non-variable filter inserts, stacked one above the other, to form a full element assembly, wherein the individual filter inserts are permanently attached to each other, preferably by way of adhesive bonding.

In this instance it may be of particular advantage to make the arrangement so that the full element assembly, together with the backflush device as a complete entity, is replaceably retained in the device housing.

The invention will now be described in greater detail by way of an exemplary embodiment shown in the drawing.

Shown are in:

FIG. 1 in schematically simplified representation a longitudinal cross-section of the exemplary embodiment of the filter device according to the invention;

FIG. 2 a device component of FIG. 1 with a filter insert in longitudinal cross-section shown enlarged compared to FIG. 1;

FIG. 3 a perspective view of a pair of flushing nozzles, shown enlarged and pulled apart explosion-like, with associated guide device disposed on the drive shaft of the exemplary embodiment;

FIG. 4 a longitudinal cross-section of the unit in FIG. 3;

FIG. 5 a partial cross-section of a filter insert corresponding to line A-A in FIG. 2;

FIG. 6 a cross-sectional representation corresponding to that in FIG. 5 along the line B-B in FIG. 2;

FIGS. 7 to 10 a perspective view of components of the filter housing of a filter insert;

FIG. 11 a perspective view of the filter housing assembled from the components in FIGS. 7 to 10, viewed from the top; and

FIG. 12 a representation according to FIG. 11, viewed from the bottom of the filter housing.

The exemplary embodiment of the filter device according to the invention shown in FIG. 1 comprises a device housing with a main housing part 1 in form of a circular cylinder, which is closed at the upper end, as shown in the drawing, by a housing cover 3 and at the lower end by a bottom part 5. A lateral inlet 7 is located within proximity of bottom part 5 through which the unfiltrate flows into a cavity 9 that forms the dirty side. Located above the inlet 7 and in the vicinity of the upper housing cover 3 is a lateral outlet 11 through which the filtrate is able to flow out from a cavity 13 that forms the clean side. The dirty side cavity 9 and the above-located clean side cavity 13 are separated by a strainer plate 15 which, as shown in FIG. 2, is provided with a circumferential annular groove 17 that forms the seat for a sealing element (not shown), which forms the seal between the dirty side and the clean side. The strainer plate 15 also serves as support for three filter inserts 19, 21 and 23, stacked one above the other, which are shown separately in FIG. 2. Of these the lower filter inserts 19 and 21 comprise a filter housing 25 with filter material 27 and a backflush device, which is shown in greater detail in FIGS. 3 to 6. The filter housing 25 of said filter inserts 19, 21 is shown in greater detail in FIGS. 7 to 12. The uppermost filter insert 23 is provided in filter housing 29 with a group of bypass valves 31 as well as a coarse filter 33. At the upper end the housing 29 of the uppermost filter insert 23 is closed by a bypass cover 35.

The backflush devices in the filter inserts 19 and 21 are attached to a drive shaft 37 that is provided in form of a hollow shaft. At a bearing point 39 on the strainer plate 15 a further hollow shaft 41 follows on from drive shaft 37, wherein the lower end of said hollow shaft 41 forms a pivot bearing and engages with a pipe socket 45, which extends from bottom part 5 into cavity 9 of the dirty side. The pipe socket 45 continues the flow path provided for backflush volumes, which starts at the drive shaft 37 in the filter inserts 19 and 21, down to an outlet 47 at the bottom part 5. A backflush valve, which is commonly provided at outlet 47, is omitted, as is the known drive that is commonly used on devices of this kind, which rotates the drive shaft 37 of the backflush device through a clutch connection with the hollow shaft 41. In a manner already known, the drive may be operated by a motor or through pressure means. For each of the lower filter inserts 19 and 21 the backflush device is provided with a pair of flushing nozzles 49, of which each pair, as shown in FIGS. 1 and 2, is attached to the drive shaft 37, rotationally offset by 180° and axially one above the other. The details of the flushing nozzles 49 are shown most clearly in FIGS. 3 to 6 and are described below.

Details for the as non-variable parts provided filter housings 25 for the lower filter inserts 19 and 20 are best shown in FIGS. 7 to 12. The filter housings 25 are provided with an upper support 51, which is shown separately in FIG. 7, as well as a lower support 53, which is shown separately in FIG. 10. As is shown most clearly in FIG. 10 for the lower support 53, both supports 51, 53 are provided with two housing walls that extend concentric to the longitudinal axis of the housing and form an intermediate space 55 between them (FIG. 10), wherein the outer housing wall is referenced with 57 and the inner one with 59. Each housing wall 57, 59 is formed by an annulus of a plurality of longitudinal bars 61 and 63 respectively, of which only a small number are referenced in FIGS. 7 and 10 for reasons of clarity. The longitudinal bars 61 and 63 of the upper support 51 extend downwards from an upper end part 64, which is formed by an annular body. Correspondingly, the longitudinal bars 61 and 63 of the lower support 53 extend from a lower end part 65, which is also formed by an annular body. The filter housing 25 is completed by the filter material 27, which is seated in the intermediate space 55 of the upper support 51 and the lower support 53. Said filter material 27 consists of a pleated web of a filter mat of at least one filter layer with a support layer in form of a lattice structure on both of its outer sides. In advantageous examples the filter fineness is in the range between 25 and 34 μm. After inserting the respective filter material 27 into the intermediate spaces 55 of the upper and lower support 51, 53 when assembling the filter housing 25, a separating wall is formed through attaching an inner support ring 66, shown in FIG. 8, to the ends of the inner longitudinal bars 63, and through attaching an outer support ring 67, shown in FIG. 9, which butts up against the free ends of the outer longitudinal bars 61. The components depicted separately in FIGS. 7 to 10, which are injection-molded from a plastic material such as PA6 and provided with an oil-proof coating if required, are then permanently attached to each other, for example through welding or preferably adhesive bonding.

With the filter housing 25 assembled from the supports 51 and 53, the longitudinal bars 61 and 63 of the lower and upper support 53 and 51 respectively are aligned to each other so that between adjacent bars 61 the outer fluid passages 69 are formed and between the inner longitudinal bars 63 the inner fluid passages 70 respectively are formed, which are only partially referenced in FIGS. 11 and 12. In the present exemplary embodiment, in which two filter inserts 19 and 21 are disposed one above the other, the filter housings 25 of the filter inserts 19 and 21 are permanently attached to each other. To this end the upper end part 64 of the lower filter housing 25 is adhesively bonded to the lower end part 65 of the upper filter housing 25.

As already mentioned, FIGS. 3 to 6 depict details of the backflush device, wherein in FIGS. 3 and 4 a pair of flushing nozzles 49 together with the respective section of the drive shaft 37 are shown separately. The pair of flushing nozzles 49 is combined into a single-piece, molded shape, which is injection-molded from a plastic material such as PA6. Disposed at the end that faces away from the drive shaft 37 is a face plate 71, oriented in axial direction, which extends over the entire height of the flushing nozzles 49 which, when in operation and with the drive shaft 37 rotating, move in the immediate proximity of the internal circumference of the inner longitudinal bars 63 of the filter housing 25. To this end the face plate 71 is provided with a slight curvature that adapts to the geometry of the inner circumference. The face plate 71 is provided with a longitudinal slot 73 that extends in axial direction and serves as inlet for the upper flushing nozzle 49, as well as a longitudinal slot 74 that also extends in axial direction and serves as inlet for the lower flushing nozzle 49.

As shown in FIG. 3, the longitudinal slots 73, 74 are offset with respect to each other in rotational direction. As is apparent from FIGS. 4 to 6, the fluid path extends in the flushing nozzles 49 from the longitudinal slot 73, 74 to a radially internally-located tubular body 75. To form the connection between the pair of flushing nozzles 49 and the drive shaft 37, an upper tube 77 and a lower tube 78 are attached to said drive shaft 37, wherein said upper and lower tubes lead into the inside of the hollow drive shaft 37. The tubes 77, 78 form together with the tubular bodies 75, which engage with said tubes, a telescope-like guide device for the pair of flushing nozzles 49. Said guide device is completed by lateral guide bars 79, which extend between the tubular bodies 75 of the flushing nozzles 49 in radial direction, wherein said guide bars 79 engage with a guide groove 80 between the tubes 77, 78 (see FIG. 3). As shown in FIGS. 4 to 6, collars 81, each of which protrudes radially inward and forms the seat for a sealing ring 82, are disposed at the radially internally positioned discharge end of the tubular bodies 75. Said sealing rings 82 consist of an elastic material so that they assume a dual function, that is, they provide not only a sealing function but also act as an energy store that applies a radially outward-directed tension on the flushing nozzles 49, which are telescopically guided by means of the guide device.

When in operation, the unfiltrate supplied via the inlet 7 passes into the dirty-side cavity 9 and from there via the passages in the strainer plate 15 into the inner cavity of the filter housings 25 of the filter inserts 19 and 21, flows through their filter material 27 during the filtration process from inside to outside towards the clean-side cavity 13 and is discharged from there via outlet 11. The backflushing action takes place with the backflush outlet 47 opened by means of the backflush valve (not shown) and with rotating flushing nozzles 49. The flow rate of the backflush volume is caused by the operating pressure of the inflowing unfiltrate, for example an oil pressure in the range between 8 and 10 bar, due to the pressure drop with respect to the open backflush outlet 47. The fluid path within the flushing nozzles 49 expands with respect to opening cross-section of the longitudinal slots 73, 74 towards the drive shaft 37, which results in a venturi effect that increases the flow velocity in the immediate vicinity of the longitudinal slots 73, 74, which facilitates the detachment of contaminants.

As a comparison of FIGS. 5 and 6 shows, the offset of the longitudinal slots 73, 74 in rotational direction is chosen such that a longitudinal slot, in the depiction of FIGS. 5 and 6 the upper longitudinal slot 73, is aligned with a longitudinal web 63 of the filter housing 25, so that the fluid path to the flushing nozzle 49 is closed, whilst at the same time the other longitudinal slot 4 is aligned with a fluid passage 70 (FIG. 6). The backflush action with this arrangement takes place essentially continually, that is, without significant pulsations of the backflush volume. At the same time the flow rate of the backflush volume is correspondingly limited since at any time the full passage cross-section of only one fluid passage 70 is available. As is also apparent from FIGS. 5 and 6, the inner webs 63 are slanted with respect to the radial direction, so that the flow direction of the flow through the longitudinal slots 73, 74 is slanted with respect to the radial direction. This causes a flow direction in the intermediate space 55 with the pleated filter material 27 in which the flow passes rather through the wide sides of the pleats of the material 27, which facilitates the cleaning action during the backflush process.

As already mentioned, a third filter insert 23 is disposed above the filter insert 21 in the depicted exemplary embodiment. The filter housing 29 of the uppermost filter insert 23 is provided with a bottom plate 84 (FIG. 2), which is attached to the upper end part 64 of the adjacent filter insert 21, for example through adhesive bonding. The bottom plate 84 is provided with a pivot bearing 85 for the upper end of the drive shaft 37, as well as valve openings 87 for the bypass valves 31 located in the filter housing 29 of the uppermost filter insert 22. Said bypass valves 31 are provided with valve bodies 89, which are preloaded into a shut-off position by means of compression springs 91 that closes the valve openings 87. If the filter material 27 of the filter inserts 19, 21 is blocked, which causes the opening of the valve openings 87, unfiltrate flows into the inner cavity of the bypass filter insert 23, exits via the coarse filter 33 and ends up in the clean-side cavity 13. Together with the coarse filter 33 this forms a safety facility which ensures the supply of oil even if the filter material 27 is blocked. 

1. A filter device, in particular for the filtration of lubricating oil, comprised of at least one filter insert (19) that retains a filter material (27), wherein said filter insert (19) is provided with fluid passages (70), which are constricted by wall parts (63) of said filter insert (19), and a backflush device (37, 49) with at least one flushing nozzle (49), which is displaceable along the inside of the respective associated filter insert (19) by means of a hollow drive shaft (37), characterized in that at least one pair of flushing nozzles (49) is provided for each filter insert (19, 21), wherein said flushing nozzles (49) are provided with longitudinal slots (73, 74) that are arranged in axial direction of the drive shaft (37) one above the other, which are offset towards each other transverse to the axial direction in such a way that, for adjacently disposed flushing nozzles (49), at least part of the longitudinal slot (73) of the one flushing nozzle (49) overlaps with at least one of the fluid passages (70) of the assignable filter insert (19, 21), and at least part of the longitudinal slot (74) of the other flushing nozzle (49) overlaps at least partially the wall parts (63) of this filter insert (19, 21) that constrict the fluid passage.
 2. The filter device according to claim 1, characterized in that the respective filter insert (19, 21) is provided with a filter housing (25) with two housing walls (57, 59) that are disposed concentrically to the longitudinal axis of the filter insert (19, 21), wherein the filter material (27) extends between said housing walls (57, 59), which are penetrated by window-like fluid passages (70).
 3. The filter device according to claim 1, characterized in that each pair of flushing nozzles (49) passes over the adjacently disposed fluid passages (70) in the filter housing by means of the motor-driven drive shaft (37) of the backflush device in succession along the inside of the respective associable, cylindrical filter insert (19, 21) in a rotatory manner.
 4. The filter device according to claim 1, characterized in that the drive shaft (37) is provided with a guide device (77, 78) for each pair of flushing nozzles (49) that protrudes in the direction towards the associable filter housing (25), wherein the respective flushing nozzle (49) engages with said guide device (77, 78) and is guided in a longitudinally displaceable manner, and wherein said flushing nozzle (49) is pressed against the inside of said filter housing (25) by way of an energy store (82).
 5. The filter device according to claim 1, characterized in that the energy store is advantageously provided in form of an elastic sealing ring (82), which presses with its one side against the drive shaft (37) and with its other side against the respective flushing nozzle (49).
 6. The filter device according to claim 1, characterized in that a pair of flushing nozzles (49) is combined into a single unit which, with its internal cross-section (75) in radial direction, ends in the hollow drive shaft (37) via the guide device (77, 78), and with its outer cross-section in radial direction leads into a longitudinal slot (73, 74) which, with respect to its dimensions, is adapted to the geometry of the respective fluid passage (70) that is passed over.
 7. The filter device according to claim 1, characterized in that both housing walls (57, 59) of a filter housing (25), which act as supports (51, 53), are closed at their opposing ends by an annular end part (64, 65), which comprises a fluid compartment for holding unfiltrate, wherein an annular separating wall passes through the filter housing (25) between the two supports (51, 53), wherein said separating wall is preferably formed by an internal (66) and an external support ring (67).
 8. The filter device according to claim 1, characterized in that longitudinal rods (61, 63) extend for each housing wall (57, 59) between the end parts (64, 65) and the separating wall (66, 67) located in between, wherein said longitudinal rods (61, 63) enclose the window-like fluid passages (69, 70) cage-like in the filter housing (25) between them.
 9. The filter device according to claim 1, characterized in that the two longitudinal slots (73, 74) of a pair of flushing nozzles (49) are offset with respect to each other so that, in conjunction with the cage arrangement of the fluid passages (70), there is always a flow path open, at least partially, preferably fully, via the one flushing nozzle (49), whilst the flow path into the other flushing nozzle (49) is at least partially, preferably fully, closed so that during a continuous rotation of the drive shaft (37) of the backflush device there is always a continuous flow through one of the two flushing nozzles (49) of a pair from the filtrate side (13).
 10. The filter device according to claim 1, characterized in that the internal longitudinal rods (63) of the cage arrangement, located adjacent to the respective pair of flushing nozzles (49), are slanted with respect to the radial direction so that they force a flow direction for each fluid passage (70) of a filter insert (19, 21), which is slanted by a predeterminable angle with respect to the inflow direction of the respective longitudinal slot (73, 74) of a pair of flushing nozzles (49).
 11. The filter device according to claim 1, characterized in that the filtration takes place from the inside of the respective filter insert (19, 21) to the outside, that the backflushing action of the respective filter insert (19, 21) takes place from outside to inside, and that the resulting backflush volumes can be discharged from the filter device via the backflush device.
 12. The filter device according to claim 1, characterized in that the respective filter insert (19, 21) is disposed stationary in a device housing (1, 3, 5), which comprises a fluid inlet (7) for unfiltrate, a fluid outlet (11) for filtrate and a discharge connection (47) for the respective backflush volume.
 13. The filter device according to claim 1, characterized in that multiple non-variable filter inserts (19, 21), stacked one above the other, form a full element assembly, and that the individual filter inserts (19, 21) are permanently attached to each other, preferably by way of adhesive bonding.
 14. The filter device according to claim 1, characterized in that the full element assembly, together with the backflush device (37, 49) as a complete entity, is replaceably retained in the device housing (1, 3, 5). 